Posted
by
samzenpus
on Friday October 14, 2011 @04:25AM
from the bringing-the-cold dept.

DesScorp writes "Science News reports on a story which blames a centuries long cooling of Europe on the discovery of the new world. Scientists contend that the native depopulation and deforestation had a chilling effect on world-wide climate. 'Trees that filled in this territory pulled billions of tons of carbon dioxide from the atmosphere, diminishing the heat-trapping capacity of the atmosphere and cooling climate, says Richard Nevle, a geochemist at Stanford University.' The story notes that the pandemics in the Americas were possibly an example of human climate manipulation predating the Industrial Revolution, though isotope measurements used during research have much uncertainty, so 'that evidence isn't conclusive.'"

I was noticing that. the summary contradicts itself. It says that the discovery caused cooling, then says that the trees reduce carbon, which reduces the heat trapping of the atmosphere. If the trees where removed and burned, increasing carbon, would not there be a warming effect from the increased heat trapping? Bad summary i suspect, but it still does not make sense to me.

A lot of the trees were not simply burned: they were used as lumber. Remember that by this point there was practically no virgin forest left in all of Europe, so finding a 20-50 m tall tree to use as the mainmast of a ship was difficult. And once you'd found the main mast, you still needed tremendous amounts of lumber for the rest of the ship. Mahogany and other tropical woods were highly valued for furniture; temperate hardwoods like oak and maple had uses for barrels, crates, and floors. (It is telling that, despite huge amounts of such woods in New England, the typical home was constructed and clad with conifers - spruce, pine, and cedar - because the hardwoods were in such demand and thus expensive.)

The general effect of this activity is to consume the forests, but not in a way that released a whole lot of carbon. Some of that carbon was eventually released (fires on ships was quite common) but plenty of it was sequestered at the bottom of the ocean (sinkings were also quite common).

There were millions and millions of Native Americans here. The Native Americans died en masse due to disease; this disease spread quickly and advanced way ahead of the Europeans. By the time Europeans got to most areas of the Americas, native populations were reduced by as much as 90% (Source: http://www.amazon.com/1491-Revelations-Americas-Before-Columbus/dp/140004006X [amazon.com]). Due to the losses in Native American populations (who did not just live "harmoniously" with nature like people are taught in school - they clear cut trees, redirected rivers, and did many things not that different from what we do today) the native management of the environment was disrupted. All the trees that they had cleared out started growing back. Increase trees-->decrease carbon-->decrease heat.

I'm not saying I think the research is sound - I have no idea, I haven't read the study - but the hypothesis is not far-fetched. The/. summary is confusing though.

Old growth forests don't capture as much carbon as new growth. Cut down a stand of 1000 year old trees and let them repopulate with all new trees and the new trees will capture carbon faster as they grow and add mass at a faster rate than the maxed out trees, while the old wood retains its carbon in the form of ships, buildings, tools, etc.

Remove a 200 year old oak tree, and it will be replaced by a dozen conifer saplings, each one adding new biomass much more quickly than the old oak that was taken away. A ton of mature oak does not have a 10th of the surface area of all those light weight saplings.

You're incorrect. The current model is roughly the same as the one from 10, 20, 30 years ago (and probably longer): we humans are not only capable but fully responsible for whatever disaster befalls us through way of the earth's climatic changes, and OMGTHESKYISFALLING.

It's the reforestation that had the huge effect, and who's to say we haven't?

I think this one might be particularly important because of the magnitude of the disaster. It wasn't just one deadly pandemic, it was half a dozen of them sweeping the Americas one after the other. The article says they estimate that close to 90% of the Native American population was wiped out over the course of less than a century by disease.

Except you have to fill in numbers. The book 1491 (mentioned above) suggests that Native American deaths from disease may have been as high as 95%; their civilizations vanished. It's an extraordinary claim, there is support in the book. The upper bound on Black Death mortality (Wikipedia) is a 60% reduction in population, which is pretty darn awful, but civilization did not vanish.

Do the majority of US citizens still believe Columbus discovered America in 1492?

Basically, I guess it's just a crap headline to draw the audience in? The article itself indicates that a mini ice age looks to have been *delayed* by European invasion, by wiping out the local population (both on purpose and accidently), they created a carbon sink of trees growing up in deforested areas, which they them later cut down. So I guess after a while the landscape looked closer to how it had been before the Europeans

Short of briefly mentioning Leif Ericsson, yes, they do. That's all they'll learn in school. Confirmed with my 17yo and 14yo within the last few years, 2 different school systems, different states (MD and NJ).

crickey, some way to go on improving the history curriculum then! Does history teaching start with the Europeans coming to the USA, or do they do go through earlier civilisations first?

Old stuff was always the most fun stuff for us here in the UK:-) loads of Celts and Romans and Saxons and Vikings charging round the place, invading and setting fire to things. A few fine castles and a couple more invasions then it all settles down to pretty boring political and social history by the renaissance...;-) (I th

They do a quick runthrough of the Clovis concept. They avoid the extinctions and don't permit much in the way of discussion about the various theories (ice free corridor? Boats?) and don't allow any potential pre-Clovis to leak into the discussion. The signs of pre-Columbian contact are similarly edited out, the first contact was Leif who stayed for a winter, and then Columbus.

I feel for authors of history books, after reading "Lies My Teacher Told Me", but things haven't gotten much better in the 15 or

Christopher Columbus - A wonderful national hero - Hawked his widely discredited and since proven wrong theory (short route to China) around all the people with money to fund his project for years until he found someone gullible enough to fund it, found a small island in mid ocean, and claimed he was right, even in face of the evidence, failed to find the whole rest of the continent, and still gets all the credit...

Forgive me for being a bit undereducated on this point, but in what way is Columbus not hugely significant in the European discovery of the Americas? Sure, there's L'Anse aux Meadows, and I've heard (though never actually read) that fishermen had discovered the Grand Banks and traded with Newfoundland, etc. But none of those were publicized and none kicked off larger rounds of exploration and colonization, so it's a bit like saying that James Watt invented the steam engine. He didn't, but he made it a lot b

"Do the majority of US citizens still believe Columbus discovered America in 1492?"

Are you saying he didn't get to America? Or, he didn't in 1492? Or, he already knew about America, so it wasn't a discovery?

That Columbus discovered the Americas doesn't imply that he was the first to discover the Americas. The first to discover the Americas were very likely Asian, and were already here (now called native Americans) by the time any known Europeans arrived.

There is evidence there was also a European migration into North America, though their contribution to the gene pool may have been not incredibly significant. Anthropologists have found tools from the west coast and east coast of North America, and have found that the west coast tools were based on Asian designs, and oddly enough, the east coast designs bared remarkable similarity to some European group's tools. There was an ice bridge between Europe and North America that people living like Eskimos could h

Well we have an easy solution to global warming then. Just depopulate America again.

America isn't the only potential candidate here... areas nearer to the equator will have a more dramatic effect since the vegetation will regrow faster. Putting an end to Brazilian cattle production would be a bigger effect than neutron bombing all of rural U.S.A.

Earlier midmillenial cool downs were due to a volcano in Iceland and other solar minimums as well.

Look, I'm infuriated by climate change denying morons myself, but rewriting history and ignoring basic science is not how you defeat those losers. Simple repetition of obvious scientific facts about man made warming is how you defeat oil and coal industry propaganda kool aid drinkers, not reimaging the plot of "Avatar."

I'm infuriated by climate change denying morons myself, but rewriting history and ignoring basic science is not how you defeat those losers.

No, but slinging a little of their own style of rhetoric back their way once in awhile does keep them inline better than always, predictably, maintaining the scientific moral high ground. The Scopes monkey trial went so badly in part because the scientific representative just couldn't think outside of his world of solid scientific proof as the final word. I had a similar experience in traffic court when the officer opened with a reading of his notebook which contained a full accounting of what he imagined

As is occurring on the national stage with the feedback we are giving Obama, sometimes you have to roll up your sleeves and go on the attack. Ideas, not people, that is, because you can't cede all bombast and fire in the belly to one side of the debate, or they dominate it.

Yes, in one regard, if one side is all zealotry and the other side is measured, people gravitate to cooler heads. On the other hand, as is the case with climate change deniers, cool heads do not sway emotional deb

I disagree - all science that relies on evidence is by definition historical.
It's a theory - we can look for evidence that supports it or disproves it, it doesn't make sense to just discount it because it is in the past.

Another line of evidence that would support such a theory:
It appears that there is historical evidence of large agricultural civilizations living in the Amazon basin before contact with European diseases and them all disappearing a short time after.
This guy was the first European to sai

"It's easy to make up stories to explain trends in data, especially when they can't be experimentally validated." Welcome to the world of science. There are very few sciences that have that level of control over experiments. Your criticism could work for anything from environmental science to evolutionary science (and much of biology) to climatology to geology to psychology to much of physics (particularly theoretical, which is doubly interesting because I know some physicists who believe it is the only rea

Where did they live? They made their own towns and cities. They didn't just come over on boats, kill all the natives and sail back to Europe did they?

No, but bringing millions via boats takes an awful long time. They didn't just show up and replace millions of natives with millions of europeans in one day. Natives died first, their fields got abandoned and forests grew in t

I suggest you read 1491: New Revelations of the Americas Before Columbus by Charles Mann for a good summary of what was happening in the Americas before Columbus and what happened when he got here. Basically, estimates put that up to 75-85% of Native Americans in many areas died from the diseases brought by the Europeans. These deaths happened months and years and decades before the Europeans got everywhere in the Americas (diseases spread quickly). It took the Europeans a long time to come close to having

I thought that during this period, one of the major sources of lighting came from whale oil and increased as colonies formed in places where whales were abundant. If reforestation on such a small scale affected the environment so dramatically, then surely so would increased CO2 release from the energy required in the progression of imperialism?

I live amongst them, along with millions of other people. Here in New England, the history is this: Prior to European settlement, 75% of the land was covered in trees. The Europeans showed up, cut down the forests and made farms of the land. At this point, roughly 25% of New England was forested, the other 75% was largely farms. Later, the farmers moved to the mid west and west, abandoning the farms in New England, which were a bitch to farm because of the rocky soil. The farms were abandoned and trees grew up in their place. That's why you can hike through forests in New England and find old foundations and very long lines of stone walls in the middle of nowhere. Back in the day, those forests were "somewhere." Even with our "sprawl" in New England, roughly 75% of the land is forested. I can attest to this as I live in a forested burb. Deer, turkeys, foxes, etc. routinely walk through my yard. Don't believe me? Then just pull up http://maps.google.com/ [google.com] and search on New England. Then look for deforested land... if you do the visual math, you'll see that it is mostly still forested here.

Sceptics of Columbus' plan were on record as saying 'Sure you'll be able to sail around the world, when hell freezes over'. He proved them wrong (sort of), and hey presto! Ice age. Coincidence? I think not!

The ironic part about this is that the Little Ice Age is actually blamed for killing off the earliest European settlement in the Western Hemisphere.

The Norse had a settlement in Greenland for almost half a millenium (from 986 AD to sometime in the 1400s), and during their better times were in contact with mainland North America ("Vinland"). As the weather turned colder, things became tougher for the Norse livestock agriculture, and better for the Inuit hunting culture. The last records we have show incres

The idea that the global climate could be changed by a relative handful of europeans clearing a tiny portion of the forested landscape with handsaws and horses is ridiculous. The Oort minimum began approximately 1,000 years ago, followed by the Wolf minimum (740 years ago), the Sporer minimum (600 years ago), and then the Maunder minimum approximately 400 years ago. Columbus set sail in 1492 so those europeans would have had to have been working like beavers (pardon the expression) to have cut down enough

Not only did you not read the article, you haven't even read any of the posts about the article clarifying things.

It goes like this:1. European Explorers get to America2. Disease wipes out tens of millions of natives3. Forests that the natives were cultivating grow back4. Carbon sucked out of the atmosphere in massive reforestation.

Pre-Columbus, the Native population of the Americas was many, many times larger than most people imagine - on the order of 80 million people. This population actively cleared land via slash-and-burn agriculture and generally comported themselves the way humans do (contrary to the popular imagination of Avatar-esque tiny populations living in perfect harmony with nature)

When Columbus made contact, he passed on smallpox and diptheria, and the subsequent wave of epidem

Coincidentally with the coldest part of the mini ice age was the "Maunder minimum" http://en.wikipedia.org/wiki/Maunder_Minimum [wikipedia.org] which was a period of very low sunspot activity. It is speculated that the two may have a common cause: variable solar radiance.

- First, this is all predicated on Europeans moving on a massive scale to the Americas. The author writes "By the end of the 15th century, between 40 million and 80 million people are thought to have been living in the Americas." Given that Columbus sailed in 1492, does anyone seriously believe tens of millions of Europeans moved to the Americas in the next 8 years? Even in the next 100 years? Completely nonsensical numbers.

The 40-80 million population refers to the natives, not the settlers.

- Third, they got the direction wrong: if forests were chopped down, they would have been burned and not allowed to regrow - thus increasing CO2, not decreasing it.

If you read the article, you;d know that the effect is due to the growth of trees in cleared areas, not the burning of trees that occurred prior to that.

Actually Darwin's theory predicts exactly this happening : the island species in his theory.

If 2 islands are artificially separated, the species that get split up with it will start to diverge, culturally and genetically. Sometimes the species can specialize enough to be truly separate, but this hardly ever happens (and it takes hundreds of thousands of years).

So what happens in most cases if previously-split populations are reunited is that one side of the split dies off entirely : contact between genes do

does anyone seriously believe tens of millions of Europeans moved to the Americas in the next 8 years?

No, people do seriously believe the European invasion killed off millions of indigenous people, who, after dying, stopped their agricultural activities, which allowed forests to regrow, which sucked CO2 out of the atmosphere.

Actually, the problem with this is more basic. No matter when you date the start of the Little Ice Age, the cooling started at least as early as 1300 (when warm summers stopped being dependable in Northern Europe) and probably around 1250 (when the North Atlantic glaciers started to expand).

More to the point, the idea that somehow the Medieval Cooling Period was caused by the discovery of the New World is yet another example of the kind of "Pay no attention to the man behind the curtain" pseudo-science that passes itself off as climate science.

Most of it is now driven by either politics (IE: People with a socialist/communist/fascist agenda that want to use climate science as a convenient crisis under which they can obtain power. See: Harry "Never let a good crisis go to waste" Reid.) or by scientists attempting to obtain/increase their funding, much of which is obtained via the former group of power-mongers.

It's part of the "perfect circle" of deceit and corruption that is at the heart of the modern left and modern climate science. Most Americans have caught on to the game by now, which is why 70% (and rising) no longer believe a word from the climate scientists' mouths. People hear the words "Climate Change" or "Global Warming" (or whatever the term du jour is) and they just roll their eyes and stop listening.

The really sad part is that it has inculcated in large parts of the American populace a distrust of scientists in general, particularly if they are in any way connected with the climate science field.

Frankly, the climate science field has been nothing but a disaster for science as a whole. It needs a hard reset, with all current scientists retiring, and all existing data deleted. We need to start over on this and do it right. Now, whether that is actually possible, I don't know. Probably not. But I don't see any other way of making it trustworthy again.

I think you have that backwards: it's not that climate deniers have come to distrust science because science has it wrong on global warming; it's that the deniers distrust science, period. Distrusting science, you're "free" to believe whatever you want to.

Unsurprisingly, such people end up believing just those things which it is in their interest to believe.

If true, this means in less than a hundred years enough CO2 was pulled out of the atmosphere to affect the environment. If proven this adds to the evidence that the climate is pretty darn fragile. I haven't read the TFA because I am getting ready to work, but there is one rebuttle and pone possible way to "test" this hypothesis off the top of my head.

The Rebuttle: I thought previous studies claimed the Little Ice Age was more regional than global. I know it affected Europe and played a hand in colonies.

The possible test: Parts of the North East U.S., namely Pennsylvania, were heavily deforested. During the Great Depressing the government sponsored Civilian Conservation Corps. walked across Pennsylvania and replanted large tracks of forest. A half of state worth of new forest popping up should at least have a little blip on CO2 level measurement, right?

A better rebuttal: Old growth forests (like those deforested from the New World) have ZERO net impact on carbon dioxide levels. A mature forest releases as much carbon dioxide (from decaying organic matter) as it releases into the atmosphere. Removing a mature forest would have minimal impact on carbon dioxide levels.

Sorry, you're right. However, reading TFA, it seems that the summary is a little too abridged. Cutting down mature forests and then planting new trees does reduce the total carbon dioxide, and that's what they're actually talking about.

Yeah, environmental scientists are good at "accidentally" not figuring in criteria like that before crying out "the sky is falling".Heat was pretty much exclusively fire ( or rubbing one bare bodkin again' another).I like the old school thinking that the Earth has changed over time and continues to do so in spite of the money we throw at environmental research. Continents go sailing the waters,crashing into one another,pockets of elements are exposed,oil come burbling to the top,forests burn out of control

Indeed, but there is no reason that I am aware of to believe that there was a significant change in the # of people burning logs.

The new world meant lumber (the primary export for so many years) used to build homes and navies in and for the old world, rather than to heat things. I'm not sure how the summary gets off with saying that reduced deforestation was happening because of the new world discovery.. the English and French, later America, were all about deforesting the new world with abandon.

Well according to the article after Europe discovered the Americas, a series of epidemics swept the Americas and may have killed close to 90% of the Native Americans. This allowed trees to grow again on land that was cleared for farmland, thus taking up some of the carbon dioxide in the atmosphere and the researchers behind this paper think that's what caused a drop in the level of CO2 that shows up at about the same time in the ice core records. That reduction in CO2 would have had a small cooling effect

I like the old school thinking that the Earth has changed over time and continues to do so in spite of the money we throw at environmental research.

True... but the thing to remember is that it doesn't change without a reason as most anti-AGW thinkers seem to imply.

Most of the big changes seem to be down to changes in atmospheric composition and we're busy changing the composition.

After watching the arguments for 15 years I don't think the human race will do a damn thing about it. Doing something would require a change in lifestyle which people will resist down to the last bullet even if leads to long-term improvements. The USA is particularly guilty o

Much of the problem will eventually resolve itself. There's a limited supply of oil, and gas prices are likely going to rise faster than inflation until they reach the point where synthetic gasoline becomes price-competitive. At point, the economic situation will likely be that you'd have to be rich, an idiot, or both to drive a gasoline powered car.

The fight now is just over whether we want to spend a smaller amount now or a larger amount later to deal with the problem. Thanks to the economic collapse i

No environmental scientist missed any criteria. A random Slashdot poster missed something for a minute.

The scientist didn't cry "the sky is falling" - you did, in your straw man. They never do, even when the evidence is pretty strong. Because fallacious attackers like you threaten their legitimate careers to defend the polluters paying to script the "Conservative" mass media attacks you parrot.

Previous climate change, along with continental drift, continental forest fires, and the other big changes you invo

Previous climate change, along with continental drift, continental forest fires, and the other big changes you invoked - all happened over thousands and millions of years. The current climate change you deniers no longer bother to deny is actually in progress is happening over just a few decades and centuries. Which is totally unprecedented.

OK then. What caused the "little ice age" to begin with? Didn't it start within a few decades or centuries? If we are to assume that Europeans deforested the Americas causing an end to the little ice age, then how did it ever start since Europeans had been deforesting Europe for centuries? Shouldn't it have been warmer in 1600's than it was in the 1400's, which should have been warmer than the 1200's and then the 800's and so on? How on earth did a little ice age form in the 1800's? Also, what ended the "big ice age" about 10,000 before Columbus was ever born?

See, this is the problem with the whole AGW argument. Man spots a trend like, the climate is warming or it's raining, and then wonder what HE did to cause it. Maybe, just maybe whatever change happened with no help from man at all. Maybe that dance really didn't cause it to rain and it was going to rain whether you danced or not.

Article's theory: An area the size of california was reforested over 200 years causing the little ice age

Your theory: removal of X amount of forest over 200 years should have resulted in Y amount of warming which we didn't see. We actually saw a temperature change of Z.

You need to figure out what X , Y and Z are before making that a legitimate argument. The article has real numbers and real research behind it, your speculation does not rise to the level of a rebuttal.

Suppose initially there's no forest. Over 100 years a forest grows, absorbing quantity X of CO2. This carbon is now locked up in the trees.

Now eventually it reaches a stable phase. Trees absorb Y amount of CO2, produce leaves, leaves fall and rot, release Y amount of CO2. Trees die, but get replaced so the forest neither grows nor shrinks. I guess that's what you mean. But the carbon that went originally into making the trees is still locked up in the forest. Burning it wi

Now eventually it reaches a stable phase. Trees absorb Y amount of CO2, produce leaves, leaves fall and rot, release Y amount of CO2. Trees die, but get replaced so the forest neither grows nor shrinks. I guess that's what you mean. But the carbon that went originally into making the trees is still locked up in the forest. Burning it will most definitely release carbon into the environment that wasn't free before.

Thus producing the OPPOSITE effect to that posited by the story.

The story speculates that forest cover increased due to depopulation of North America by diseases and weapons brought by European settlers. The resulting increase in biomass was allegedly responsible for a reduction in CO2 leading to global cooling.

The whole conjecture sounds like BS with a politically correct slant. In Europe there was an ongoing deforestation which had commenced a century or so before Columbus, and a considerable deforestation of the Americas started a century or so later. Due to the time scales of forest growth and the probable extent of any net change in forest cover, the effect on climate would have been rather limited (probably negligible).

Er, no, it's entirely consistent. The important part is the forest growing. There was an X amount of CO2 in the air, trees grew and locked up a part of it. Where do you see the opposite effect happening?

The story speculates that forest cover increased due to depopulation of North America by diseases and weapons brought by European settlers. The resulting increase in biomass was allegedly responsible for a reduction in CO2 leading to global cool

Michael Mann agrees with you that other processes better explain the little ice age. FTA:

Natural processes may have also played a role in cooling off Europe: a decrease in solar activity, an increase in volcanic activity or colder oceans capable of absorbing more carbon dioxide. These phenomena better explain regional climate patterns during the Little Ice Age, says Michael Mann, a climate researcher at Pennsylvania State University in State College.

Indeed you didn't read the article. Its premise is that RE-forestation (new growth) caused by existing native populations being wiped out by imported disease caused the untended cleared areas used by theose native populations for agriculture and other things to be filled in with NEW forest, which caused CO2 to drop, decreasing temperatures.

As usual, the "Conservative" agenda is to lie by attacking their opponent falsely for precisely what the "Conservatives" actually are.

You mean "racists"? Yeah! Herman Cain is the worst! Don't even get me started on that Bobby Jindal. Arnold Schwarzenegger will be the first to tell you how us "Conservatives" won't tolerate them damn foreigners!

Oh wait! You probably actually believe it. See, it's funny because you accuse conservatives of lying, all while believing and even perpetuating lies AGAINST conservatives.

The "politically correct" thinking on climate change is the denial. The polluters pay for politics to fight the science that might make them pay for the pollution.

Yeah, that worked out so well for Rick Perry. Fact is, if you so much as say, "Maybe we don't know all there is to know abo

I never said anything about racism. Though it's easy to see what's racist about the fetishes for Cain on the one hand (by only 25% of Republicans) and Jindal (who, in Louisiana, is "not Black or Mexican", which is all that counts there - where I lived for several years).

What the post to which I replied said was not "maybe we don't know all there is to know about climate change". That's a statement with which I, and practically all climatologists, to say nothing of just reasonable people, agree. It's you "Co

In the USA, it's politically correct to believe that global warming is a hoax - but if it isn't, it's not caused by people

Oh, please, that's nuts. You think that corporations spend millions of dollars advertising how green they are because they're struggling against political correctness? You think that schools spend hours our of every week teaching kids about climate change and green lifestyles because the teachers are struggling against political correctness? You're making a losing argument, an ob

Some are worse than others. Some love to paint with a broad brush using open ended phrases like your "Climate Change Skeptics".

Skeptic about which claims? There are hundreds of climate change issues and there equally hundreds of opposing opinions. Each side has their facts so where does a skeptic fall? I tend to agree with some and disagree with others yet under your banner I am lumped in with the kooks.

There is a whole industry out there which only tries to assign guilt, much of it to gain moral superiority but quite a bit is built on making a profit. Climate change discussions didn't get very far until some very large companies learned how to use politicians to make a lot of money off of it. Look at GE, poster child of abusing this process, we give them two billion dollars to further develop wind technologies which is already in their best interest to do so? They then pile on the deductions to have nearly an effective zero rate of taxes?

The real climate skeptics should be applauded because most of science is being used to hide an agenda whose only goal is to pad specific pockets. Its well funded and marketed and much of it has governments behind it because the politicians love money.

From TFS: "Tying together many different lines of evidence, Nevle estimated how much carbon all those new trees would have consumed. He says it was enough to account for most or all of the sudden drop in atmospheric carbon dioxide recorded in Antarctic ice during the 16th and 17th centuries."

From TFA that 'sudden drop' in CO2 levels equates to 6 - 10 ppm. Given that the current atmospheric concentration is 392 ppm, and in 2009 CO2 levels increased by 2ppm, we're talking about tiny quantities well within the margin of error of the measuring methods used. At worst we're talking about an equivalent to 5 years of increase, based on the 2009 figure, and that was enough to trigger a mini 'ice age'? This is junk science.

It might be, but if the reforestation alone can account for that drop in atmospheric CO2 (that's a lot of forest!), then the change in the landscape itself would certainly have an influence on local climate, possibly enough to influence Western Europe.

Also, don't be so quick to dismiss research based on an article in a popular science magazine: most journalists are incompetent, and will try to get a sensationalist angle out of anything and nothing.

The current value and a yearly change have little bearing on the margin of error. Sure when the measured change is very small compared with the total value then measurement error comes into play but 3 significant figures isn't exactly an unheard of level of precision.

Sure that may be well within the margin of error but given you provided no evidence of that being the case and I'm too lazy to do any research myself I think I'll take the word of the Standford University geochemist over a random slashdot post

really? i was under the impression that a major portion of the native american population was at least semi nomadic, with only a small portion being agrarian societies. If you can show me solid evidence that I am miss-informed, I would be most appreciative.

This [amazon.com] is a roundup of a lot of scholarly work on what the Americas were like before Columbus. In short, the book contends that there were an awful lot of people in North America prior to the Age of Exploration who were extraordinarily susceptible to European diseases. While many practiced straight-up agriculture, a lot of others essentially "farmed" wild game - early European colonists into the Ohio Valley noted that the land often looked like European parks (i.e., trees spaced far enough apart that wagons could easily be driven between them, with occasional copses, making perfect habitat for deer), and that an extraordinarily high percentage of the trees that were there were nut-producers (i.e., they planted those and cut down anything else). It also argues that the early explorers (especially de Soto's expedition) weren't making things up when they talked about cities with tens of thousands of inhabitants lining the sides of rivers. When they died en masse, the "old-growth" forests arose.

You're responding to the summary. The article at ScienceNews has a different flavor.

This hypothesis builds on a previous idea that, after disease-resistant Europeans met native populations, diseases spread throughout the New World in simultaneous epidemics. There is evidence for this, including a pattern of entire New World civilizations, far inland from where Europeans settled, collapsing within a generation of their earliest arrivals. For a comparison, the Plague in Europe is known to have killed betwe

Except that the ice records show something consistent with large scale reforestation, somewhere on the planet. This is interesting. It's also less about the people, and more about the plants, and what land was cleared for new farms for new people in other places.